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pair trawlers

Bass pair-trawl fishery

Pair trawling for bass in the south west of England has been demonstrated to have high levels of cetacean by-catch. Sea trials conducted by the Sea Mammal Research Unit (SMRU) showed that there was no easy technical solution for reducing by-catch levels through the use of mitigation devices. As a result of the findings Defra banned pelagic pair trawling for bass by UK vessels within 12 miles of the south west coast of England (within ICES area VIIe) in December 2004. Other bass fisheries, such as gillnetting and hand lining, and pair trawl fisheries targeting other species have not been affected.

The UK asked that the ban on pelagic pair trawling for bass be extended to the vessels of other Member States, who are currently permitted to fish between 6 and 12 miles off the south west English coast (under Article 9 of Council Regulation EC No 2371/2002), but this was turned down by the European Commission.

There is ongoing research funded by Defra and carried out by the Sea Mammal Research Unit to monitor bycatch in the limited UK bass pair-trawl fishery beyond 12 miles.



Pair Trawling

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Pair trawling is a fishing activity carried out by two boats, with one towing each warp (the towing cables). As the mouth of the net is kept open by the lateral pull of the individual vessels, otter boards are not required. By utilising the towing power of two boats, and as no otter boards are needed, a larger net may be worked than would otherwise be possible, or alternatively, the two boats can share increased fuel efficiency.

As doors are not necessary, the gear arrangements are simplified, with the warps attaching directly to the wings of the net. Setting and hauling of the nets are carried out by one boat, while the other is only used for towing; usually each will take turns at these operations.

Pair Trawling started in Korea and China but was later banned after the marine resources of these two countries was nearly depleted as a result of the method. Both China and Korea have little or nothing left in terms of marine resources in that part of the world because of pair trawling.

Pair trawling is effective on all demersal species. In shallow waters, where the noise from a single vessel may scatter fish, two vessels operating a distance apart tend to herd fish into the path of the net. Catch per vessel often considerably exceeds that attainable through standard bottom trawling. Pair trawlers  have reported an average increase per vessel in catches of an order of three to six times that from single trawler operations .

Pair Seine is very similar to pair trawling but longer lengths (as much as 3500metres) of seine net ropes and
combination wire are used instead of trawl warp. It is usually used to sweep vast areas of clean
ground, whereas pair trawl covers smaller areas of harder seabeds. One of the problems of both methods is that the two vessels have to come close together to pass the tails of the net across. This can be hazardous in poor weather.

Because of the increased efficiency of pair trawling, vessels are able to tow their gears in mid-water at a faster speed to target species which are normally able to escape trawl nets, such as the European seabass. This has caused some controversy, due to the high level of marine mammal bycatch associated, leading to the British government introducing a ban on pair trawling for bass in UK territorial waters. See side bar.

Pair-trawling generally occurs between the months of November and April and, sure enough, the greatest numbers of dolphin strandings occur at the same time.

By-catch is completely indiscriminate. It takes the young and the old - everyone gets involved.

Written in death

Sometimes, signs of their miserable death can be found on their bodies during post-mortem.

They are trapped underwater in the nets, and they react by closing their blow holes,. They fight to get free, and this can last for many minutes; you can read the signs of this struggle on their bodies - cuts on their snouts, broken teeth and damaged fins.

dead dolphin


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